1. Field of the Invention
The present invention relates to a method of surface mounting a connector on a printed circuit board, and a connector, and more particularly, to a method of surface mounting a connector by fixing the connector to a printed circuit board prior to reflow soldering, and a connector.
2. Description of the Related Art
In recent years, a system adapted to data communications comes to be placed in an environment equipped with a STM (Synchronous Transfer Mode) node, a remote access user receiving module, a fast IN (Intelligent Networks) service control node, and an ATM (Asynchronous Transfer Mode) node. A printed circuit board for each node, particularly one for the remote access user receiving module, has main component parts thereof mounted by the SMT (Surface Mount Technology) due to the necessity for mass production thereof. Of the main component parts, terminals of connectors for connecting the module are also surface mounted.
Conventionally, the surface mount is carried out by the following procedure: Soldering paste is printed on a printed circuit board. Each component chip is mounted on the printed circuit board printed with the soldering paste. The resulting printed circuit board is placed in a reflow furnace whereby the soldering paste is melted to solder the component chips.
FIGS. 22(A) and 22(B) show an example of the construction of a conventional connector for surface mount. FIG. 22(A) is a plan view of the connector, while FIG. 22(B) is a cross-sectional view take on line X.sub.0 --X.sub.0 of FIG. 22(A). The connector 90 has a body 91, and a plurality of long lead pins 91a and a plurality of short lead pins 91b extending from the body 91. These lead pins 91a, 91b are placed on a pattern of a printed circuit board. Within the body 91, there are provided female terminals 91c, 91d each electrically connected to a corresponding one of the lead pins 91a, 91b. The female terminals 91c, 91d have male terminals inserted therein from a casing via respective through holes 91e, 91f of the body 91.
Further, the body 91 of the connector 90 has arms 92, 93 formed on opposite sides thereof for protection of the lead pins 91a, 91b. These arms 92, 93 are formed with rivet holes 92a, 93a.
The connector 90 constructed as above is first positioned on the printed circuit board such that the lead pins 91a, 91b are located on respective pads of the pattern. In this state, rivets are inserted through the rivet holes 92a, 93a, respectively, and the connector 90 is fixed to the printed circuit board by these rivets. After having the other chips mounted or placed thereon, the printed circuit board is placed in a reflow furnace to carry out the reflow process for soldering the chips to the printed circuit board.
Since the connector 90 is fixed to the printed circuit board by the rivets, there is no fear of displacement thereof before the soldering. The lead pins 91a, 91b receive downward urging forces so that they are positively brought into intimate contact with the pads. Further, after the printed circuit board is completed, male connectors are frequently inserted and removed from the connector 90 for inspection of quality thereof. However, breaking stress can be prevented from being applied to the soldered portions during the frequent inspections.
To meet the above-mentioned ends, various connectors other than the one having the construction illustrated in FIGS. 22(A) and 22(B) are manufactured. For instance, Japanese Laid-Open Patent Publication (Kokai) No. 5-347174 discloses a connector formed with arms having respective hook members on opposite sides thereof, the arms being fitted in respective cutouts formed in a printed circuit board to have the connector fixed to the printed circuit board. Japanese Laid-Open Patent Publication (Kokai) No. 7-211409 discloses a connector formed with a hook-shaped locking member and a hooking portion, for use with a printed circuit board formed with a locking hole and a cutout portion. The locking member and the hooking portion of the connector are fitted in the locking hole and the cutout portion of the printed circuit board, respectively, whereby the connector is fixed to the printed circuit board.
In the case of the connector shown in FIGS. 22(A) and 22(B), application of a force of approximately 200 grams is required to insert the rivets into the rivet holes 92a, 93a, respectively. However, an ordinary automatic component-mounting system is capable of exerting a small force of several tens grams for urging each chip to the printed circuit board. Therefore, conventionally, the rivets are required to be inserted into the respective rivet holes by manual operations, which leads to a degraded productivity. Although it is also possible to provide a dedicated apparatus for the riveting, this leads to a large increase in the manufacturing cost and hence is not practical.
On the other hand, the connectors disclosed in Japanese Laid-Open Patent Publication (Kokai) Nos. 5-347174 and 7-211409 cannot have their above-mentioned fixing members properly fitted merely by placing the connectors on the respective printed circuit boards, and hence after all, manual operations are required in the surface mounting.